In recent years, there have been significant advances in laser technology including solid state laser technology, and lasers are used in numerous applications including scientific research, manufacturing, medicine, security, communications, and a growing number of additional applications. Many of the applications of lasers require lasers that are capable of reliably providing high power outputs or at least outputs with a tunable or selectable output power level. To this end, numerous mechanisms have been developed to try to achieve the required power classes of lasers. For example, certain laser applications involve pulse lasers or lasers operating under pulsed conditions, and a number of amplifiers have been produced to provide an output beam or pulse that provides gain from an input or seed beam or pulse.
High power laser amplifiers have a wide variety of applications and come in many forms, but each amplifier generally functions to amplify the power of an input pulse or beam to output an amplified pulse or beam. Design of laser amplifiers may be limited by factors related to the tolerance of optical components in the amplifier to pulses of high-energy laser light and average power loading. For example, in one large class of amplifier designs, known as regenerative amplifiers, multiple passes through a single gain medium or plural gain media are used for efficient extraction of gain. In these regenerative amplifiers, an optical path is defined around which an input pulse makes a number of passes before being coupled out as an amplified pulse. A regenerative amplifier is a device that is used for strong amplification of optical pulses, e.g., laser pulses with ultrashort pulse durations in the picosecond or femtosecond ranges. Multiple passes through the gain medium, such as a solid state medium, are achieved by placing the gain medium in an optical resonator, together with an optical switch that may be formed by an electro-optic modulator and one or more polarizers. The number of round trips in the resonator is controlled with the optical switch, and when this number is large a high overall amplification factor (i.e., gain) can be achieved.